1. Field of the Invention
The invention relates to the measurement and control of gases and more particularly to the measurement and control of the hydrogen concentration in liquid and gaseous sodium.
2. Description of the Prior Art
Typical prior art diffusion type hydrogen measuring systems have utilized a thin membrane positioned in the sodium and a hydrogen detection system to measure the rate at which hydrogen diffused through the membrane. Typically, the membranes were formed from thin walled tubes of stainless steel or nickel with one end closed and the second end connected to the hydrogen detection system. The sensitivity of these systems was significantly influenced by the thickness of the membrane. Typical membranes were relatively thick because many applications required the membrane to be subjected to pressures in the range of 10 atmospheres and temperatures up to 1000.degree.F.
Typically, the prior art membranes are positioned in the sodium stream and welded in place. This made changing the membrane without disturbing the sodium stream rather difficult if not impossible. This feature contributed significantly to the service problems of the system because the membranes must be changed when fouling of the surface of the membrane changes the rate of hydrogen diffusion through the membrane.